A hard disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces. When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read-write head that is positioned over a specific location of a disk by an actuator. A read-write head makes use of magnetic fields to write data to, and read data from the surface of a magnetic-recording disk. A write head works by using the current flowing through its coil to produce a magnetic field. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head produces a localized magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.
There is a commercial demand for high-capacity digital data storage systems, in which multiple data storage devices (DSDs) are housed in a common enclosure. A DSD, such as an HDD, may undergo rigid body rotation in response to any number of environmental vibration sources, especially in a multi-HDD storage system. Such rotation may be the result of, for example, airflow and acoustic energy from system fans, mechanical coupling among neighbor HDDs, other external disturbances transmitted through a common system motherboard and/or electrical connectors, and the like. In order to compensate for read-write head off-track issues due to HDD rotational vibration that is transmitted to the read-write head, such as from the HDD enclosure base, rotational vibration (RV) feed-forward systems are implemented into some HDDs. However, as HDD data tracks become narrower and narrower and system environments in which HDDs are installed generate more and more vibrational energy within the system (e.g., because of increased HDD density within the system, and system motherboard temperature demands, which require higher RPM fan usage), the frequency range of the vibration (and thus the energy) experienced by the HDDs is rising (e.g., above 2 kHz) and classical approaches to compensating for the effects of rotational vibration may no longer be effective enough.
Any approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.